Just watched Requiem for a Dream. Amazing movie, no wonder it as an 8.5 on IMDB.
The movie explores the life of four people, as their addictions get out of control. Yes, the movie is about drug addiction and its perils, but there's absolutely no preaching. Only the haunting depiction of the painful reality. And that's where the movie really shines.
There are no drug lords or gang wars, and neither do they focus on the profitability of the industry (remember Blow). It's about how ordinary people get drawn in and how it gets too late before they realise the shattering of their dreams.
The soundtrack is amazing (though creepy) and augments the realistic visuals.
I'd certainly give it 9/10. So, if you happen to come across this movie, don't let it slip.